Way OT I know, but there isn't a direct linear relationship between electricity use and coal burnt. Huge amounts of power get dumped to ground overnight in baseload power stations because it takes hours to take a generator module down then reheat & synchronise it to the grid. So a heap of excess power is generated and dumped overnight.

2 corollaries to this are:
1. "Earth hour" does not reduce CO2 emissions by any amount despite the warm glow it gives the participants.
2. A significant number of plug-in hybrids can be recharged overnight without increasing CO2 emissions from power stations... they would just use up the excess off-peak electricity that gets wasted now... and the same amount of coal would still be burnt.

There would therefore be a nett benefit from replacing dino-fuelled cars with plugin hybrids.

I have copied this discussion from the Biodiesel Forum, where it was Off Topic.

1. Coal fired power stations do take time to come up to full power. Power authorities do study the TV programs to know when to add more generation during commercial breaks.
2. Electricity is never "dumped to ground ", as this would damage the equipment, it is much easier than that, they vent steam to prevent the generator speeding up too much at low load.
3. At low load times, they do not put as much coal on the fire, so there is less steam being generated.
4. They know when to build up steam at any time of day or night, due to employment patterns, schools, industry starting up, etc. There is a long history of power supply and demand management, and they are good at it.
5. Gas fired power stations can be started from cold and be running at full power much faster and are used for load peaking management.
6. There IS a direct relationship between power consumed and CO2 emissions.
7. Earth Hour does reduce emissions, but the effect is very small due to the short time frame and the small number of participants, as well as the fact that industry does not often participate.

I would like to know how you developed the idea that power was dumped to ground overnight.
I hope this explains the power industry a little better.

Regards,
Tony

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I was told this by an engineer who worked on the design, construction and commissioning of the last 2 major coal-fired power stations built in the Hunter Valley. He gave me a very detailed description of how coal-fired generation works, which makes some your points questionable at best, points 2 and 3 particularly.

Remember the "generators" are really alternators, ie they generate AC current. Accordingly, each unit must be synchronised to the grid so the frequency and phase match. It takes time to spin a generator up to the correct speed and phase before it can be connected to the grid. I would have to check this, but the figure of 90 minutes comes to mind.

The power stations quoted to me as examples are modular in design, they each contain generator modules of 660MW each. These are either online or offline at any time, ie they contribute 660MW or zip to the grid. There is no in-between,

I take your point about capacity matching, but this is not a short-term thing. They can't vary generation capacity by simply slowing down a generator by venting steam or feeding less coal. They have to put modules on- or off-line, 660 megawatts at a time. The ideal situation, from the power company's POV, is to have excess electricity generated at all times to cover short-term spikes.

This is why we have off-peak tariffs. They are an incentive for consumers to use some of the excess output that would otherwise be dumped to ground. Yes it does happen, the equipment is designed to do this without damage. If electricity generators could reduce their output overnight and sell it at full price, they would, because it would be more profitable to do so. This fact alone is compelling evidence that my engineer friend is right.

Im not really up on power generation on the sort of scale that is being discussed here (telemetry and control on gas pipelines seems to be the rut Im stuck in at the moment), but I have been doing the numbers on electric versus fossil fuel transport.
All the preliminary research I have done thus far suggests that the amount of carbon generated for X km driven on fossil fuel is around 50 to 60% higher than using coal fired power to charge the batteries to propel the electric car the same distance.
The numbers are slightly variable depending on what fuel you look at, but not by much.
The numbers also vary slightly if you use AC or DC propulsion systems (as the battery requirements are a bit different), but once again the numbers seem to only vary by a few percentage points.
The important thing to keep in mind here is that both electric cars and, dare I say it for fear of being branded a heretic, biofuels are only stop gap measures until R&D produces something that relies on neither of the above or fossil fuels. Eventually it will happen, maybe not in my lifetime (of which there is still a fair bit to go) but there will be a workable solution at some point in the future.
Its also worth keeping in the back of your mind that each side of the arguement has its own set of figures to wheel out when needed.
I belong to the Electric vehicle forums and have seen a similar set of figures to counter the biofuels in the same way. I dont think there is really any animosity on either side of the arguement, just two seperate groups with different means of achieving the same end.

My 2c Worth

If anyone has any references that might help me, please feel free to PM me with a link.

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Rgds

Adam

"Revolution never comes with a warning!"

I don't have any particular barrow to push here either, I know what you mean about alternative fuels, electric cars etc being stopgaps until a real solution comes along that can be as reliable and economically-viable as what we have now. I expect we will see a period of 20-30 years where a range of competing technologies will coexist, much like the first few decades of motorised transport.

And there are little-recognised wildcards too. ZECA (the Zero Emission Coal Alliance) seems to be well under the radar of most who are interested in CO2 reduction. Their efforts are based on getting the energy out of coal without having to burn it, by the dual channels of hydrogen extraction and exothermic carbonate production with the carbon left behind. The theory is that this approach will yield hydrogen in commercial quantities for fuel cells, and heat to power steam-driven generation, with lime as the main by-product. And no CO2.

Somehow I think that predictions of a "post-coal future" might not eventuate for a couple of centuries or so.